Any vehicle equipped with an O2 sensor is also equipped with a 3-way Cat.
The Vanagon uses this set up to eliminate the need for an EGR valve.  Lean
mixtures and high compression increase peak flame temperatures.  This
increases the production of NOx.  Over advance timing also contributes to
NOx.

Dennis
-----Original Message-----
From: David Bayer <bayer@sybase.com>
To: vanagon@zuni.likeminds.com <vanagon@zuni.likeminds.com>
Date: Tuesday, February 17, 1998 10:44 PM
Subject: Re: NOx emissions (WAS: '85 Westy failing Pa. emissions)

>>| mixture is leaner; but not that much higher.  THe high NOx actually
>>| comes from when the 3-way catalyst's NOx conversion efficiency takes a
>>| dive from the lean mixture.  A three-way cat can effectively handle CO
>>| and HC when lean (and there is less produced due to the added oxygen
>>| during combustion).  That is why lean-NOx cats are being developed for
>>| diesel and gasoline direct injection engines.
>
> I do not believe any of the vanagons have three way cats. I could
>be wrong on this though...
>
>dave
>
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